The invention relates to a method and apparatus for facilitating movement of a heat exchanger tube bundle between various maintenance stations after removal of the heat exchanger tube bundle from the heat exchanger shell. In the past, either the heat exchanger tube bundle withdrawal apparatus itself is utilized for moving the removed heat exchanger tube bundle from one maintenance station to another (such as shown in U.S. Pat. No. 3,458,063), or slings have been utilized either for moving the removed bundle to a separate movable support for subsequent transfer to cleaning operations (see U.S. Pat. No. 3,958,698), or for lifting the tube bundle from one maintenance station to another. While the necessary end results can be achieved with such prior systems, there are drawbacks associated therewith. For instance, when the extraction mechanism itself it utilized for moving the tube bundle between maintenance stations, compromises must be made in its design that can adversely affect its ability to perform its primary withdrawal function, and the entire apparatus is tied up the entire time a single tube bundle is being cleaned or repaired. Where slings are utilized, such slings can, and often do, result in damage to the heat exchanger tube bundles, requiring further repair thereof.
According to the present invention a method is provided for performing maintenance operations on a heat exchanger tube bundle that eliminates many drawbacks associated with prior systems, and in general provides for quick, safe, and effective handling and maintenance of heat exchanger tube bundles between the withdrawal and re-insertion operations. The invention also contemplates an apparatus facilitating practice of the method. The primary focus of the method according to the invention is the provision of movable trollies which are provided beneath the tube bundle at predetermined spaced points along the length thereof to support the weight thereof during the extraction operation, and the utilization of such same trollies to move the tube bundle off of the frame structure and subsequently onto desired maintenance stations.
The present invention contemplates a method for performing maintenance operations on a heat exchanger tube bundle mounted in a heat exchanger shell utilizing an extracting and inserting apparatus including a frame structure having a plurality of movable trollies supported for movement therewith and for supporting the tube bundle at spaced points along the length thereof, the trollies having rollers disposed on opposite sides of the central axis of the tube bundle. The method comprises the following steps: (a) Linearly moving the tube bundle to pull it out of the heat exchanger shell onto the frame structure. (b) Providing the trollies beneath the tube bundle at predetermined spaced points along the length thereof in engagement therewith to support the weight of the tube bundle. (c) Moving the frame structure with supported tube bundle to a supported position wherein the central axis of the tube bundle is substantially horizontal. (d) Rolling the trollies, with supported tube bundle, off of the frame structure by moving the tube bundle horizontally with the trolley rollers rolling along a stationary horizontal support. (e) Moving the tube bundle while still supported by the trollies to desired maintenance (e.g. cleaning and/or repair) stations at which maintenance operations are performed on the tube bundle while still supported by the trollies. (f) Rolling the trollies supported by the tube bundle back onto the frame structure while the frame structure is in a horizontal position. (g) Moving the frame structure into operative association with the heat exchanger shell; and (h) Linearly moving the tube bundle off of the frame structure into the heat exchanger shell.
Preferably the rolling step is practiced by rolling the movable trollies onto a protector, the protector including a platform that is horizontal and has a trolley support structure vertically coincident with a trolly support structure of the frame structure. The method preferably consists essentially of such steps, whereby the tube bundle never is supported by slings, with the steps being performed substantially sequentially. The maintenance station moving step may include moving the tube bundle to a washing station and spraying washing fluid onto the tube bundle while it is being rotated about its central axis, and to accomplish this the tube bundles may be transferred from the movable trollies to a second set of movable trollies, the movable trollies of the second set effecting the rotation of the bundle. The movable trollies are latched into position onto the protector platform so that no relative movement therebetween is possible, and preferably an alignment structure is provided for aligning the protector with the frame structure. The protector and the frame structure are aligned just before rolling of the trollies onto or off of the frame structure, and disconnection of the alignment structure from between the protector and the frame structure is positively prevented by control interlocks until the latching step is accomplished. The maintenance steps may be further accomplished by transferring the tube bundle while supported by the trollies off of the protector and into an automated cleaning system. Movement between stations can be accomplished by lifting the entire protector with a crane, or by jacking the protector platform off the ground and disposing a mobile apparatus underneath it.
The protector apparatus for use in facilitating practice of the method according to the invention includes a platform including a guide structure associated therewith corresponding to the guide structure of the frame structure, and being long enough to support all of the trollies associated with the frame structure when they support a tube bundle thereon; and means for facilitating movement of the platform from one maintenance station to another. Means are associated with the protector for positively aligning it with a frame structure, for effecting latching of the movable trollies onto the platform, and for interlocking the latching and alignment structures to prevent disconnection of the alignment structure until the latching means effect latching of the trollies onto the platform. A linear force exerting structure may also be associated with the protector for moving the tube bundle supported by the trollies off the protector into an automated cleaning system or the like.
Suitable frame structures for insertion and removal of heat exchanger tube bundles into and from a heat exchanger shell that are utilized in practicing the present invention are disclosed in copending application Ser. No. 923,443 filed July 10, 1978, now U.S. Pat. No. 4,227,854, and U.S. Application Ser. No. 102,983 filed by John B. C. Davies entitled "CORE EXTRACTION AND INSERTION APPARATUS", on Dec. 11, 1979, the disclosure of both of said applications being incorporated by reference herein.
It is the primary object of the present invention to provide a simple, safe, and effective method and apparatus for practicing maintenance operations on a heat exchanger tube bundle while removed from a heat exchanger shell. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.